Hibernate Annotation (Hibernate 注解)

进入：http://www.hibernate.org

说明文档：

英文：http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/

中文：http://docs.jboss.org/hibernate/annotations/3.4/reference/zh_cn/html_single/

下载：hibernate annotation 3.4.0 GA

得到：hibernate-annotations.jar

　　　hibernate-commons-annotation.jar

　　　ejb3-persistence.jar

数据库：mysql

category表：id，name，description <Pk>id

product表：id,name ,price, description ,category_id <pk>id <fk>category_id

新建java project项目：

Add Hibernate Capabilities

hibernate.cfg.xml

<?xml version='1.0' encoding='UTF-8'?>

<!DOCTYPE hibernate-configuration PUBLIC

"-//Hibernate/Hibernate Configuration DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools. -->

<hibernate-configuration>

<session-factory>

<property name="dialect">

org.hibernate.dialect.MySQLDialect

</property>

<property name="connection.url">

jdbc:mysql://localhost:3307/users

</property>

<property name="connection.username">root</property>

<property name="connection.password">root</property>

<property name="connection.driver_class">

com.mysql.jdbc.Driver

</property>

<property name="myeclipse.connection.profile">

mysqlusers

</property>

<property name="format_sql">true</property>

<property name="show_sql">true</property>

<property name="current_session_context_class">thread</property>

<mapping class="com.b510.examples.Product" />

<mapping class="com.b510.examples.Category" />

</session-factory>

</hibernate-configuration>

利用Hibernate的逆向工程生成：

Category.java and Product.java

Category.java

package com.b510.examples;

import java.util.HashSet;

import java.util.Set;

// 标准注解

import javax.persistence.CascadeType;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.FetchType;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.OneToMany;

import javax.persistence.Table;

//增加的注解

import org.hibernate.annotations.GenericGenerator;

//当前的类是一个持久化类，是Category这个类。他映射了一个表category。所对应的 数据库是users

//这句：@Table(name = "category", catalog = "users") 可以省略

@Entity

@Table(name = "category", catalog = "users")

public class Category implements java.io.Serializable {

private static final long serialVersionUID = 3240281547213597385L;

private Integer id;

private String name;

private String description;

private Set<Product> products = new HashSet<Product>(0);

public Category() {

}

public Category(String name, String description, Set<Product> products) {

this.name = name;

this.description = description;

this.products = products;

}

// 主键 ：@Id 主键生成方式：strategy = "increment"

//映射表中id这个字段，不能为空，并且是唯一的

@GenericGenerator(name = "generator", strategy = "increment")

@Id

@GeneratedValue(generator = "generator")

@Column(name = "id", unique = true, nullable = false)

public Integer getId() {

return this.id;

}

public void setId(Integer id) {

this.id = id;

}

//映射表中name这个字段 ，长度是500

@Column(name = "name", length = 500)

public String getName() {

return this.name;

}

public void setName(String name) {

this.name = name;

}

//映射表中description这个字段 ，长度是500

@Column(name = "description", length = 500)

public String getDescription() {

return this.description;

}

public void setDescription(String description) {

this.description = description;

}

//级联操作：cascade = CascadeType.ALL

//延迟加载：fetch = FetchType.LAZY

//映射：mappedBy = "category"

//一对多方式

@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "category")

public Set<Product> getProducts() {

return this.products;

}

public void setProducts(Set<Product> products) {

this.products = products;

}

}

Product.java

package com.b510.examples;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.FetchType;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.JoinColumn;

import javax.persistence.ManyToOne;

import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

@Entity

@Table(name = "product", catalog = "users")

public class Product implements java.io.Serializable {

private static final long serialVersionUID = -1546206493725028472L;

private Integer id;

private Category category;

private String name;

private String price;

private String descripton;

public Product() {

}

public Product(Category category, String name, String price,

String descripton) {

this.category = category;

this.name = name;

this.price = price;

this.descripton = descripton;

}

@GenericGenerator(name = "generator", strategy = "increment")

@Id

@GeneratedValue(generator = "generator")

@Column(name = "id", unique = true, nullable = false)

public Integer getId() {

return this.id;

}

public void setId(Integer id) {

this.id = id;

}

//延迟加载：多对一方式

//关联信息：外键name = "category_id"

@ManyToOne(fetch = FetchType.LAZY)

@JoinColumn(name = "category_id")

public Category getCategory() {

return this.category;

}

public void setCategory(Category category) {

this.category = category;

}

@Column(name = "name", length = 500)

public String getName() {

return this.name;

}

public void setName(String name) {

this.name = name;

}

@Column(name = "price", length = 10)

public String getPrice() {

return this.price;

}

public void setPrice(String price) {

this.price = price;

}

@Column(name = "descripton", length = 500)

public String getDescripton() {

return this.descripton;

}

public void setDescripton(String descripton) {

this.descripton = descripton;

}

}

测试代码：

HibernateTest.java
/**

*

*/

package com.b510.examples;

import java.util.Set;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.AnnotationConfiguration;

import org.hibernate.cfg.Configuration;

/**

*

* @author XHW

*

* @date 2011-7-20

*

*/

public class HibernateTest {

public static void main(String[] args) {

HibernateTest test=new HibernateTest();

test.add();

test.find();

}

public void add(){

Configuration config=new AnnotationConfiguration();

config.configure();

SessionFactory sessionFactory=config.buildSessionFactory();

Session session=sessionFactory.getCurrentSession();

session.beginTransaction();

Category c=(Category)session.get(Category.class, 5);

Product p=new Product();

p.setName("计算机科学与技术");

p.setPrice("123");

p.setDescripton("计算机科学与技术,好啊，真是红啊");

p.setCategory(c);

c.getProducts().add(p);

session.save(p);

session.getTransaction().commit();

}

public void find(){

Configuration config=new AnnotationConfiguration();

config.configure();

SessionFactory sessionFactory=config.buildSessionFactory();

Session session=sessionFactory.getCurrentSession();

session.beginTransaction();

Category c=(Category)session.get(Category.class, 5);

System.out.println("id: "+c.getId()+" name:"+c.getName());

Set<Product> p=c.getProducts();

for(Product product:p){

System.out.println("id:"+product.getId()+" name:"+product.getName()+" description:"+product.getDescripton());

}

session.getTransaction().commit();

}

}

运行效果：

log4j:WARN
No appenders could be found for logger (org.hibernate.cfg.annotations.Version).

log4j:WARN Please initialize the log4j system properly.

Hibernate:

select

category0_.id as id1_0_,

category0_.description as descript2_1_0_,

category0_.name as name1_0_

from

users.category category0_

where

category0_.id=?

Hibernate:

select

products0_.category_id as category5_1_,

products0_.id as id1_,

products0_.id as id0_0_,

products0_.category_id as category5_0_0_,

products0_.descripton as descripton0_0_,

products0_.name as name0_0_,

products0_.price as price0_0_

from

users.product products0_

where

products0_.category_id=?

Hibernate:

select

max(id)

from

product

Hibernate:

insert

into

users.product

(category_id, descripton, name, price, id)

values

(?, ?, ?, ?, ?)

Hibernate:

select

category0_.id as id5_0_,

category0_.description as descript2_5_0_,

category0_.name as name5_0_

from

users.category category0_

where

category0_.id=?

id: 5 name:xml33

Hibernate:

select

products0_.category_id as category5_1_,

products0_.id as id1_,

products0_.id as id4_0_,

products0_.category_id as category5_4_0_,

products0_.descripton as descripton4_0_,

products0_.name as name4_0_,

products0_.price as price4_0_

from

users.product products0_

where

products0_.category_id=?

id:9 name:计算机科学与技术 description:计算机科学与技术,好啊，真是红啊